Over the past several years a growing family of leukocyte chemoattractant/activating factors, termed chemokines, has been described (Oppenheim, J. J. et al., Annu. Rev. Immunol., 9:617-648 (1991); Schall and Bacon, Curr. Opin. Inmunol., 6:865-873 (1994); Baggiolini, M., et al., Adv. Immunol., 55:97-179 (1994)). Members of this family are produced and secreted by many cell types in response to early inflammatory mediators such as IL-1xcex2 or TNFxcex1. The chemokine superfamily comprises two main branches: the xcex1-chemokines (or CXC chemokines) and the xcex2-chemokines (CC chemokines). The xcex1-chemokine branch includes proteins such as IL-8, neutrophil activating peptide-2 (NAP-2), melanoma growth stimulatory activity (MGSA/gro or GROxcex1), and ENA-78, each of which have attracting and activating effects predominantly on neutrophils. The members of the xcex1-chemokine branch affect other cell types such as monocytes, lymphocytes, basophils, and eosinophils (Oppenheim, J. J. et al., Annu. Rev. Immunol., 9:617-648 (1991); Baggiolini, M., et al., Adv. Immunol., 55:97-179 (1994); Miller and Krangel, Crit. Rev. Immunol., 12:17-46 (1992); Jose, P. J., et al., J. Exp. Med., 179:881-118 (1994); Ponath, P. D., et al., J. Clin. Invest., 97:604-612 (1996)), and include proteins such as monocyte chemotactic proteins 1-4 (MCP-1, MCP-2, MCP-3, and MCP-4), RANTES, and macrophage inflammatory proteins (MIP-1xcex1, MIP-1xcex2). Recently a new class of membrane-bound chemokines designated CX3C chemokines has been identified (Bazan, J. F., et al., Nature 385:640-644 (1997)). Chemokines can mediate a range of pro-inflammatory effects on leukocytes, such as triggering of chemotaxis, degranulation, synthesis of lipid mediators, and integrin activation (Oppenheim, J. J. et al., Annu. Rev. Immunol., 9:617-648 (1991); Baggiolini, M., et al., Adv. Immunol., 55:97-179 (1994); Miller, M. D. and Krangel, M. S., Crit. Rev. Immunol., 12:17-46 (1992)). Lately, certain xcex2-chemokines have been shown to suppress HIV-1 infection of human T cell lines in vitro (Cocchi, F., et al., Science (Wash. D.C.), 270:1811-1815 (1995)).
Chemokines bind to 7 transmembrane spanning (7TMS) G protein-coupled receptors (Murphy, P. M., Annu. Rev. Immunol., 12:593-633 (1994)). Some known receptors for the CC or xcex2 chemokines include CCR 1, which binds MIP-1xcex1 and RANTES (Neote, K., et al., Cell, 72:415-425 (1993); Gao, J. L., J. Exp. Med., 177:1421-1427 (1993)); CCR2, which binds chemokines including MCP-1, MCP-2, MCP-3 and MCP-4 (Charo, I. F., et al., Proc. Natl. Acad. Sci. USA, 91:2752-2756 (1994); Myers, S. J., et al., J. Biol. Chem., 270:5786-5792 (1995); Gong et al., J. Biol Chem 272:11682-11685 (1997); Garcia-Zepeda et al., J. Immunol. 157:5613-5626 (1996)); CCR3, which binds chemokines including eotaxin, RANTES and MCP-3 (Ponath, P. D., et al., J. Exp. Med., 183:2437-2448 (1996)); CCR4, which has been found to signal in response to MCP-1, MIP-1xcex1, and RANTES (Power, C. A., et al., J. Biol. Chem., 270:19495-19500 (1995)); and CCR5, which has been shown to signal in response to MIP-1xcex1, MIP-1xcex2 and RANTES (Boring, L., et al., J. Biol. Chem., 271 (13):7551-7558 (1996); Raport, C. J., J. Biol. Chem., 271:17161-17166 (1996); and Samson, M. et al., Biochemistry, 35:3362-3367(1996)).
CCR2 is expressed on the surface of several leukocyte subsets, and appears to be expressed in two slightly different forms (CCR2a and CCR2b) due to alternative splicing of the mRNA encoding the carboxy-terminal region (Charo et al., Proc. Natl. Acad. Sci. USA 91:2752-2756 (1994)). MCP-1 acts upon monocytes, lymphocytes and basophils, inducing chemotaxis, granule release, respiratory burst and histamine and cytokine release. Studies have suggested that MCP-1 is implicated in the pathology of diseases such as rheumatoid arthritis, atherosclerosis, granulomatous diseases and multiple sclerosis (Koch, J. Clin. Invest. 90:772-79 (1992); Hosaka et al., Clin. Exp. Immunol. 97:451-457 (1994); Schwartz et al., Am. J. Cardiol. 71(6):9B-14B (1993); Schimmer et al., J. Immunol. 160:1466-1471 (1998); Flory et al., Lab. Invest. 69:396-404 (1993); Gong et al., J. Exp. Med. 186:131-137 (1997)). Additionally, CCR2 can act as a co-receptor for HIV (Connor et al., J. Exp. Med. 185:621-628 (1997)). Thus, CCR2 receptor antagonists may represent a new class of important therapeutic agents.
The present invention relates to an antibody (immunoglobulin) or functional fragment thereof (e.g., an antigen-binding fragment) which binds to a mammalian CC-chemokine receptor 2 (also referred to as CCR2, CKR-2, MCP-1RA or MCP-1RB) or portion of the receptor (anti-CCR2). In one embodiment, the antibody of the present invention or fragment thereof has specificity for human or rhesus CCR2 or a portion thereof. In another embodiment, the antibody or fragment of the invention blocks binding of a ligand (e.g., MCP-1, MCP-2, MCP-3, MCP-4) to the receptor and inhibits function associated with binding of the ligand to the receptor (e.g., leukocyte trafficking). For example, as described herein, antibodies and fragments thereof of the present invention which bind human or rhesus CCR2 or a portion thereof, can block binding of a chemokine (e.g., MCP-1, MCP-2, MCP-3, MCP-4) to the receptor and inhibit function associated with binding of the chemokine to the receptor. In one embodiment, the antibody is monoclonal antibody (mAb) LS132.1D9 (1D9) or an antibody which can compete with 1D9 for binding to human CCR2 or a portion of human CCR2. Functional fragments of the foregoing antibodies are also envisioned.
In another embodiment, the antibody or functional fragment of the present invention binds human CCR2 or a portion thereof, and inhibits human immunodeficiency virus (HIV) binding to the receptor, thereby inhibiting function associated with binding of HIV to the receptor (e.g., HIV antigen release and infectivity). In one embodiment, the antibody is monoclonal antibody 1D9 or an antibody which can compete with 1D9 for binding to human CCR2 or a portion of human CCR2.
The present invention also relates to an antibody or functional fragment thereof (e.g., an antigen-binding fragment) which binds to a mammalian CCR2 or portion of the receptor and provides increased fluorescent staining intensity of CCR2 or compositions comprising CCR2 relative to other anti-CCR2 antibodies. In one embodiment, the antibody is monoclonal antibody 1D9 or LS132.8G2 (8G2) or an antibody which can compete with 1D9 or 8G2 for binding to human CCR2 or a portion of human CCR2.
The present invention further relates to a method of inhibiting the interaction of a cell bearing mammalian (e.g., human, non-human primate or murine) CCR2 with a ligand thereof, comprising contacting the cell with an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR2 or a portion of CCR2. Suitable cells include granulocytes, leukocytes, such as monocytes, macrophages, basophils and eosinophils, mast cells, and lymphocytes including T cells (e.g., CD8+cells, CD4+cells, CD25+cells, CD45RO+cells), and other cells expressing CCR2 such as a recombinant cell expressing CCR2 (e.g., transfected cells). In a particular embodiment, the antibody is 1D9 or an antibody which can compete with 1D9 for binding to human CCR2 or a portion of human CCR2.
Another embodiment of the invention relates to a method of inhibiting the interaction of a cell bearing mammalian CCR2 with a chemokine, comprising contacting said cell with an effective amount of an antibody or functional fragment thereof which binds to CCR2 or a portion of said receptor. In one embodiment of the method, the antibody or functional fragment thereof is any one or more of 1D9, an antigen-binding fragment of 1D9 or an antibody or fragment thereof having an epitopic specificity which is the same as or similar to that of 1D9. Furthermore, the invention relates to a method of inhibiting a function associated with binding of a chemokine to CCR2, comprising administering an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR2 protein or a portion of said receptor. In one aspect of the method, the antibody or functional fragment thereof is any one or more of 1D9, an antigen-binding fragment of 1D9 or an antibody or fragment thereof having an epitopic specificity which is the same as or similar to that of 1D9.
Another aspect of the invention is a method of identifying expression of a mammalian CCR2 or portion of the receptor by a cell. According to the method, a composition comprising a cell or fraction thereof (e.g., a membrane fraction) is contacted with an antibody or functional fragment thereof (e.g., 1D9 or 8G2) which binds to a mammalian CCR2 protein or portion of the receptor under conditions appropriate for binding of the antibody thereto, and the formation of a complex between said antibody or fragment and said protein or portion thereof is detected. Detection of the complex, directly or indirectly, indicates the presence of the receptor on the cell. The present invention also relates to a kit for use in detecting the presence of CCR2 or a portion thereof in a biological sample, comprising an antibody or functional fragment thereof which binds to a mammalian CC-chemokine receptor 2 or a portion of said receptor, and one or more ancillary reagents suitable for detecting the presence of a complex between said antibody or fragment and said protein or portion thereof.
Also encompassed by the present invention are methods of identifying additional ligands or other substances which bind a mammalian CCR2 protein, including inhibitors and/or promoters of mammalian CCR2 function. For example, agents having the same or a similar binding specificity as that of an antibody of the present invention or functional fragment thereof can be identified by a competition assay with said antibody or fragment. Thus, the present invention also encompasses methods of identifying ligands or other substances which bind the CCR2 receptor, including inhibitors (e.g., antagonists) or promoters (e.g., agonists) of receptor function. In one embodiment, cells which naturally express CCR2 receptor protein or suitable host cells which have been engineered to express a CCR2 receptor or variant encoded by a nucleic acid introduced into said cells are used in an assay to identify and assess the efficacy of ligands, inhibitors or promoters of receptor function. Such cells are also useful in assessing the function of the expressed receptor protein or polypeptide.
Thus, the invention also relates to a method of detecting or identifying an agent which binds a mammalian CCR2 or ligand binding variant thereof, comprising combining an agent to be tested, an antibody or antigen-binding fragment of the present invention (e.g., monoclonal antibody 1D9, an antibody having an epitopic specificity which is the same as or similar to that of 1D9, antigen-binding fragments of 1D9, monoclonal antibody 8G2, an antibody having an epitopic specificity which is the same as or similar to that of 8G2, and antigen-binding fragments of 8G2) and a composition comprising a mammalian CCR2 protein or a ligand binding variant thereof. The foregoing components can be combined under conditions suitable for binding of the antibody or antigen-binding fragment to mammalian CCR2 protein or a ligand binding variant thereof, and binding of the antibody or fragment to the mammalian CCR2 protein or ligand binding variant is detected or measured, either directly or indirectly, according to methods described herein or other suitable methods. A decrease in the amount of complex formed relative to a suitable control (e.g., in the absence of the agent to be tested) is indicative that the agent binds said receptor or variant. The composition comprising a mammalian CCR2 protein or a ligand binding variant thereof can be a membrane fraction of a cell bearing recombinant CCR2 protein or ligand binding variant thereof. The antibody or fragment thereof can be labeled with a label such as a radioisotope, spin label, antigen label, enzyme label, fluorescent group and chemiluminescent group. These and similar assays can be used to detect agents, including ligands (e.g., chemokines which interact with CCR2) or other substances, including inhibitors or promoters of receptor function, which can bind CCR2 and compete with the antibodies described herein for binding to the receptor.
According to the present invention, ligands, inhibitors or promoters of receptor function can be identified in a suitable assay, and further assessed for therapeutic effect. Inhibitors of receptor function can be used to inhibit (reduce or prevent) receptor activity, and ligands and/or promoters can be used to induce (trigger or enhance) normal receptor function where indicated. The present invention also provides a method of treating inflammatory diseases, autoimmune diseases, atherosclerosis, and graft rejection, or HIV infection, comprising administering an inhibitor of receptor function (e.g., chemokine binding or HIV binding) to an individual (e.g., a mammal, such as a human). The present invention further provides a method of stimulating receptor function by administering a novel ligand or promoter to an individual, providing a new approach to selective stimulation of leukocyte function, which is useful, for example, in the treatment of infectious diseases and cancer.
Another aspect of the invention relates to a method of inhibiting HIV infection of a cell which expresses a mammalian CCR2 or portion thereof, comprising contacting the cell with an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR2 or portion of the receptor and inhibits HIV binding and infection. In a particular embodiment of the invention, the antibody or functional fragment thereof is any of 1D9, an antibody having an epitopic specificity which is the same as or similar to that of 1D9, an antibody which can compete with 1D9 for binding to human CCR2, and antigen-binding fragments thereof.
Also encompassed by the present invention is a method of inhibiting (e.g., treating) HIV in a patient, comprising administering to the patient an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR2 or a portion of said receptor and inhibits HIV binding to the CCR2 receptor. The anti-CCR2 antibody or fragment can be administered alone or in combination with one or more additional therapeutic agents, e.g., one or more antibodies which bind a co-receptor for HIV infection and inhibit binding to said co-receptor, such as an anti-CCR3, anti-CCR5, and/or anti-CXCR4 antibody.
Another aspect of the invention also relates to a method of preventing or inhibiting HIV infection in an individual, comprising administering to the individual an effective amount of an antibody or functional fragment thereof which binds to CCR2 and inhibits HIV binding to CCR2. According to the method, preventing HIV infection includes treatment in order to prevent (reduce or eliminate) infection of new cells in an infected individual or in order to prevent infection in an individual who may be, may have been or has been exposed to HIV. For example, individuals such as an HIV infected individual, a fetus of an HIV infected female, or a health care worker can be treated according to the method of the present invention.
The present invention also encompasses a method of inhibiting leukocyte trafficking in a patient, comprising administering to the patient an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR2 or portion of said receptor and inhibits function associated with binding of a ligand to the receptor.
The present invention also relates to a method of inhibiting or treating CCR2-mediated disorders, such as inflammatory disorders, comprising administering to a patient an effective amount of an antibody or functional fragment thereof which binds to a mammalian CCR2 or portion of said receptor and inhibits CCR2-mediated function.
The present invention further relates to an antibody or fragment thereof as described herein (e.g., monoclonal antibody 1D9 or an antigen-binding fragment thereof) for use in therapy (including prophylaxis) or diagnosis, and to the use of such an antibody or fragment for the manufacture of a medicament for the treatment of a CCR2-mediated disorder, or other disease or inflammatory condition as described herein.